Crack Paths 2012

four point bending tests have been performed on three identical specimens, produced

with a C20/25 concrete and DRAMIX-RC-80/0.60-BNfibres, characterised by a length

of 60 mm, a diameter equal to 0.75 mm, and a fibre dosage equal to 30 kg/m3. The

specimens were under-reinforced, since the provided reinforcement ratio ρ has been

kept equal to 0.00315. In addition, a transversal reinforcement constituted by 8 m m

stirrups, with 1 0 0 m mspacing, has been included in the beams. More details about

reinforcement distribution and material properties can be found in [8] and are partly

summarised in Fig. 4, where also geometrical details of the test are indicated.

P

2φ8

φ8

3 5 0

2φ12+1φ8

250

100 600

100

600

600

Figure 4. Sketch of the loading arrangement adopted during the experimental test and

beamcross-section details [8] (dimensions in mm).

Taking advantage of the symmetry of the problem, only one half of the SFRCbeam

has been modelled, by adopting a FE mesh constituted by quadratic, isoparametric 8

node membraneelements with reduced integration (4 Gauss integration points).

250

load [kN]

200

150

100

Experimental [8]

Numerical

50

displacement [0.01 m m ]

0

0

2000

4000

6000

8000

(a)

(b)

Figure 5. Comparisons between numerical and experimental [8] results, in terms of: (a)

applied load vs. deflection at midspan; (b) crack pattern at failure.

The main comparisons between experimental and numerical results have been

provided in terms of load-deflection response, as well as crack pattern at failure, and are

summarised in Fig. 5. As can be observed, the adopted procedure is able to correctly

predict the experimental failure load, even if the maximumachieved deflection at

midspan is slightly underestimated. As regards the crack pattern at failure, both the

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